Come to think of it, I would send a bill to the BMW dealer who busted it originally. Not that it will be paid but, just to show defiance, your grit and competence in the face of the dealer's incompetence and poorly skilled mechanic.

On the invoice I would print, To repair and correct damage caused by incompetent dealer technician.

In your last photo, the tap is shown in a typical tap wrench with the quill of the milling machine above the work. Are you hand tapping using the quill as a reference? Also, what tapping fluid did you use during tapping? Was there any difficulty during the tapping process with the original threads being overcut?

Finally, alloy can be rather buttery or very difficult to machine. Did you ascertain the alloy used in the case before proceeding? What rod was used to provide the alloy fill?

Since MJ is off riding his new bike, I'm going to say what I think def.

He hand tapped that hole using a pin in the chuck to center the tap using the dimple in the top of the tap.
A little down force is all that is needed to get it started straight.
Once you get it started straight, it tends to stay that way. I'd be careful almost all the way through on this job.
I usually chuck the tap and power it in part way, then stop and go manual after that because I don't have a tapping head yet.

I've tapped a pile of holes this way but never anything that big in that critical an application.
Although, with all due respect, he had nothing to lose at that point.

I bet the case would machine like butter, however, I don't know how it would be after he welded it.
I'd also like to know.

__________________
Mike
So far, everything that has surprised me has been completely unexpected.

Since MJ is off riding his new bike, I'm going to say what I think def.

He hand tapped that hole using a pin in the chuck to center the tap using the dimple in the top of the tap. That's what I was thinking, as well.
A little down force is all that is needed to get it started straight.
Once you get it started straight, it tends to stay that way. I'd be careful almost all the way through on this job. Fortunately, this was not a blind hole.
I usually chuck the tap and power it in part way, then stop and go manual after that because I don't have a tapping head yet.

I've tapped a pile of holes this way but never anything that big in that critical an application.
Although, with all due respect, he had nothing to lose at that point.

I bet the case would machine like butter, however, I don't know how it would be after he welded it. Some alloys are a bit brittle after welding.
I'd also like to know.

As a prototype machinst (~1970), I used to tap holes from 2-56 up to 1 inch in alloy and steel plate using a Bridgeport Vertical Mill (manual, no NC). I too chucked the tap and allowed the mill to center and rotate the tap but allowed the threads to feed the tap. My thinking was once the tap was started, it was best to keep constant pressure on the tap to preclude breaking the tap (which I did on several occasions).

Also, this hands off approach allowed me to apply cutting fluid and compressed air as the tap cut threads. Those were fun days when I learned a lot about metallurgy and just how tough some metals were and were not.

Alloys were always challenging for me. Most of my work was in alloy. Steel was more predictable to cut. I've never tried much welding. I had a friend who could weld steel and alloy beer cans together without blowing holes in the work...very steady hands and lots of patience.

In your last photo, the tap is shown in a typical tap wrench with the quill of the milling machine above the work. Are you hand tapping using the quill as a reference? Also, what tapping fluid did you use during tapping? Was there any difficulty during the tapping process with the original threads being overcut?

Finally, alloy can be rather buttery or very difficult to machine. Did you ascertain the alloy used in the case before proceeding? What rod was used to provide the alloy fill?

Thank you. Continued good luck.

Hi def;

I used the method outlined by MotorradMike, using the quill with a pin in a collet to steady the tap and keep it centered as it started the hole. For tapping fluid I just used some light penetrating oil that I had lying around in a can, it was a generic version of WD40. Worked quite well. I did make sure to go slow, though; when you are working on your own bike your heart always beats a little faster!

As far as the welding is concerned, I deferred to the expertise of my colleague, who is a trained welder. He said to choose a filler rod for general purpose aluminum welding (4043) to play it safe.

I am always looking to learn more, so if you see something that wasn't quite right or if you have some experience to share do let me know. I think I've learnt a hell of a lot from this little incident! I just hope someone else benefits from the collective expertise here.

I used the method outlined by MotorradMike, using the quill with a pin in a collet to steady the tap and keep it centered as it started the hole. For tapping fluid I just used some light penetrating oil that I had lying around in a can, it was a generic version of WD40. Worked quite well. I did make sure to go slow, though; when you are working on your own bike your heart always beats a little faster!

As far as the welding is concerned, I deferred to the expertise of my colleague, who is a trained welder. He said to choose a filler rod for general purpose aluminum welding (4043) to play it safe.

I am always looking to learn more, so if you see something that wasn't quite right or if you have some experience to share do let me know. I think I've learnt a hell of a lot from this little incident! I just hope someone else benefits from the collective expertise here.

With patience and wisdom and some grit thrown in for good measure, you turned a bad situation into one with a good outcome. Many less skilled would have either incurred a large repair bill or sold their bike.

I would let the dealer know of the success of your repairs and somehow convey to him that you have no faith in his skills and his business practices don't inspire customer loyalty or patronizing his business...in other words, he should be ashamed of the way you were treated (not to mention your bike).

Apologies for not having updated you earlier on the outcome of this little mess.

The gearbox is all done. Although the dealer would not pay for the repair, I raised enough of a stink that they covered the cost of the removing and reinstalling the gearbox, as well as the labour associated with the overhaul. There was also a 25% discount on parts given.

Before the 'box was reinstalled I powdercoated it to match the rest of the bike. Just to be safe, I picked up a pair of Touratech frame reinforcing hard parts which promptly went on with the gearbox.

And THEN...

My final drive failed. BUT since it had been about a year since the SAME DEALERSHIP overhauled it, I could not have it repaired under warranty. So I'm going to learn how to do it myself and post the results here . Want a job done well? Do it yerself!

Sorry to hear about your trouble and I can't offer any advice about repair or replacement, but I'd say that it's the dealer/mechanics fault and I'd be expecting them to sort it out. Something should have told the mechanic/expert who you paid good money to effect a repair on your vehicle, that something was amiss when he had to extend the breaker bar. Any dope would know that something would break, it's only alloy for goodness sake! Looks like he just used brute force to extract the pin rather than heat it up to soften the Loctite on the thread. Hope you get sorted!

Using a breaker bar on the joint in question without heating the joint/threads which are well known to be secured with Loctite and subsequently damaging the case is the work of a hack not a mechanic.

Such damage is unforgivable and shows a lack of experience, skill and knowledge of how the bike is assembled and how it should be disassembled.

It appears that the proper documents were not consulted before the work was begun; again, unforgivable....that's what the damn manuals are for...to help the technician from making an error such as we see here.

Also, the BMW dealer in question should be made public and should know that we know who the he is.

I've been in old, dirt floor Triumph and H-D shops where the mechanics used extreme care when working on customers motorcycles. Those shops are now mostly gone, replaced by well equipped shops with professional mechanics. To hear of an broken alloy case by a so-called mechanic is unforgivable.

Once, I was working on a H-D carburetor and I broke one of the tabs that holds the float pin....completely my fault. Now, I could have made out that the tab was pooly cast or some other excuse but, I knew that I made the error. The carburetor body was replaced at my expense.

I just don't trust shops to do the work as well as I can or with as much care...after all, its not their bike.